


Vault 66

by Inscripsi



Category: Fallout (Video Games), Undertale (Video Game)
Genre: AU, Alternate Universe, Alternate Universe - Fallout (Video Games) Setting, Alternate Universe No One Asked For, Dark Sans (Undertale), Eventual Relationships, Eventual Romance, Eventual Smut, F.E.V., F/M, FEV Virus, Fallout Video Game References, Ghoul Sans, Ghouls, Human Experimentation, No resets, Nonbinary Frisk (Undertale), Pacifist Frisk (Undertale), Post-Fallout: New Vegas, Post-War, Post-War America, Psychic Abilities, Reader Is Not Frisk (Undertale), Sans (Undertale) Needs a Hug, Slow Build, Slow Burn, Smut, The Institute (Fallout), Vault 100, Vault 66, pre-Fallout 4, vault-tec
Language: English
Status: In-Progress
Published: 2020-03-13
Updated: 2020-12-04
Packaged: 2021-03-01 04:42:06
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 9
Words: 18,442
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23129491
Author URL: https://archiveofourown.org/users/Inscripsi/pseuds/Inscripsi
Summary: It's a simple enough job. You find the kid, you get the caps. The job doesn't really matter at the end of the day, as long as you're the only one doing the footwork.But Frisk just ran from one Vault only to fall into another. And this one is full of monsters.
Relationships: Sans (Undertale)/Reader
Comments: 38
Kudos: 81





	1. Chapter 1

“So you either can’t or _won’t_ , tell me how long _exactly_ this child has been missing. _The only child in your vault._ You have no idea if they might have been kidnapped, or if they made contact with anyone outside of the vault. And you want me to base my search for them on a handful of drawings and journal entries with the promise of payment but only a tenth of the caps upfront?”

Frustrating though these circumstances are, you already know you’re going to end up taking this case. You’ve got orders. They don’t know you already have the upper hand in information. That doesn’t mean you won’t sit here and make this dressed down Vault-Tec bureaucrat shake in his standard-issue boots a bit. Vault 100 was being less than forthcoming about the issue facing them. A child had gone missing on their watch. If you could get answers through intimidation instead of reconnaissance, then all the better. The lab tech- Ernie, if the stitched on name tag was to be believed- shifted his clipboard to clasp his hands together, poorly smoothing down his harried expression. 

“We’ve been assured by our contacts outside of the Vault that your agents are some of the best trackers in the Corvega area-”

“Yes, but even the best trackers need something to work with when they’ve got no history with the client in question, no leads on what direction they may have gone, and _no solid motive_.”

Ernie shuffles his feet a bit and looks through the papers tucked on his clipboard. It slowly becomes obvious that pushing this line of inquiry much more will lead to them either shutting you down or shutting you out. A disinterested sigh, not entirely feigned, escapes you as he reaches the bottom of his stack of redacted documents, prior frustration waning, “Listen, the most important thing you can give me is more of a timeline. I can’t run off after this kid unless I know how far they might have gotten.”

It was for the best not to spook them altogether. If you could tease out any extra details, all the better, but you’d rather not risk running this as a free agent. It meant they’d hire competition, and you were here explicitly to postpone that outcome. His expression smooths by a fraction almost immediately, “Of course. We don’t expect you to work miracles, the Overseer has put together a dossier for Frisk. It isn’t available until we’ve had someone commit to taking on the case, however. I’m sure you understand.” 

The saccharine-sweet practiced bureaucracy edges its way back in as he speaks, comfort easing his features into geniality again. You feel compelled to offer a small tug of your lips upward, a nod toward selling him on the idea that his mannerisms were working, “And so you’ve called in the best to ensure that the job gets done.” 

The smug hunter is always an easy act to lean into, it’s what people have come to expect in a wasteland of bounty hunters and the slave trade. Nevermind that the asking price behind your particular brand of hunting started at nearly double the going rate. You don’t often encounter people who can appreciate why you cost so much to hire on, and especially wouldn’t among these sallow, frail dwellers out of Vault 100. They were locked into their superior, _safe_ way of life and gave you the distinct impression that they felt you should consider yourself lucky for even having seen this much of it. Cocky blowhards. 

Ernie has eased up enough to stroke your ego, knowing his role in the game once again thanks to your front of bravado. “ _Precisely_. You and your guild are the first we’ve offered this contract to, you know.”

The bold lie makes your arms tense up, but you don’t make any action out of the motion. Your pride has already risen into this matter too much and you don’t want to risk making a scene based on knowledge he doesn’t know you have. But the assumption of your ignorance rubs you the wrong way. You’re a Venerie for fuck’s sake. Most people would know not to dick around with someone in your position. You have to make your peace with the conclusion that its vault-dweller ignorance wrapped up in the effort of flattery. 

“Of course. You knew you wouldn’t have to ask anyone else if you came to us first. The Venerie always deliver.”

The smile he flashes again at your alluded agreement to the case is all smarm, peppered with some genuine relief. Whether that’s at his belief that the lie went unnoticed or the idea that their quest to find someone to undertake this nightmare of a missing person case is unclear. What is clear is that his ‘morning coffee’ attitude is back to stay, “So I should arrange for you to meet with Overseer Sentas for a full debriefing?” 

The annoyance flairs back up enough to threaten your mask of bravado, but you tamp it down to sell your quick, “Absolutely,” with enough derisive bluster to satisfy the situation. It’s not like _they_ knew you didn’t have a choice.

* * *

Vault 100 situated itself on the Southern highway leading out of the Grand Rapids area, fortunately situated amongst a swath of wildlife that had been a pre-War nature preserve between the aforementioned city and a now whimsically named ghost town, known pre-War as Kalamazoo. The Vault was one of the last spots on the civilized map before bearing northward into the Great Lake-marshes, depending on who and when you asked. Grand Rapids, the only northern competition that was structurally sound, faced the plight of any urban area in a contested fallout zone, a constant barrage of factions vying for leadership. Most of these were small raider gangs, with the occasional cult or would-be-beneficiary group. Few of them lasted out a month. 

Most people with any sense just stayed south of the I-94, where there was enough blanket protection from the sprawl of New Corvega that they didn’t have to worry overmuch. Thankfully for Vault 100, there was less uncertainty surrounding the Northern wasteland in years past. They’d emerged from their century underground to establish themselves as a trading outpost despite their bizarre tendencies, and thrived from their perfect location between Detroit, Chicago, and New Corvega. The fact that Grand Rapids was a pinnacle of wasteland life didn’t matter as much if there was somewhere “civil” to hole away a few miles south. 

The fact of the matter was that Vault 100 never really joined in wasteland life, they had a directive that led them to stay apart. Theirs was a culture that could only be afforded by Vault-Tec, full of arranged marriages and precise breeding, scheduled to maintain population control. They occasionally dipped into the wastes to replenish where scheduled efficiency had given way to biological imperfections, but their waiting list was decades-long by now. 

So you had been called in, explicitly out of the Vault’s desire to hire on someone who wouldn’t wheedle for a position in their carefully choreographed hierarchy. How lucky for everyone involved that the practice was an alienating concept at best for you, and downright unnerving if you stopped to think on it too long. 

It also was the reason this particular case of theirs was so downright peculiar. Centennials, as they monikered themselves in the wastes, adhered religiously to their strict birthing regimen and breeding program which was outlined by the Vault AI. They had children in waves, each family aiming to have two children five or ten years apart precisely. There weren’t resources for kids in lean years, however, and so Vault 100 didn’t have a single soul below the age of fourteen. Except for Frisk.

Much as you could have expected, the dossier on the small fry leaves a lot to be desired, and Overseer Sentas isn’t any more forthcoming. Given the grainy Vault-Tec photo that was taken for their ID passcard sometime within the last year, you would’ve placed the kid somewhere around eight. So you knew now they looked a little older than they actually were, but not by much. The nondescript mussed-bob haircut and less than enthused facial expression contributes leagues towards an idea of their personality though, which you had no real prior context for.

Everything else on them was more or less redacted, including their family information and living quarters in the vault. You expected as much, but it was interesting to see where you could fill in the holes.

“Frisk came about due to… special circumstances. Their family is no longer housed within the vault, but we didn’t see fit to banish a babe that hadn’t any control in the circumstance of its birth. The mother asked us to keep it, and so we have.” Overseer Sentas has a clipped, harsh mannerism about her way of speaking on Frisk that leaves you bristling on their behalf. 

You suppose it's a cultural difference, but you can’t help the twitch in your pinky every time she refers to the kid as ‘it’ in that magnanimous way. The whole conversation leaves you with more questions about Vault 100 than you’ve had answers, and they certainly hadn't shied away from outright lying. You aren’t sure how much they’re holding out on you, but you’ve been in this kind of work long enough to know that no one in this situation has the best of intentions for Frisk. While you were included on that list, you had to wonder where your intentions for the kid ranked next to those of the Overseer or the Vault.

* * *

Three hours after being buzzed in and whisked underground you emerge from Vault 100 bleary-eyed and desperately thankful for the marshy, overcast wasteland air. It wasn’t what you’d call fresh, but at least it wasn’t canned. Stretching out the clinical chill that was only achieved through underground insulation and functioning Vault-grade air conditioning, you readjusted to the open road wariness of the wasteland. You had a kid to find. But first, there were a few calls to make.

**Notes for the Chapter:**

> [09/20] I am going through and updating with edits before finally resuming with work on chapters. These first few chapters are a little more Fallout heavy to set the scene, then they'll be swerving more heavily into Undertale. Not sure how the overall balance will work for those unfamiliar with one fandom or another, but I will try to keep it approachable. Please feel free to DM if you have any questions. Hope you enjoy!


	2. Chapter 2

Frisk had never known life with friendship before they were given a Pip-Boy. Everything in the Vault had been a series of tests or the reward for their completion, including any and all socialization. Despite this, they had grown up into someone relatively well-mannered for their lot in life.

Director Yoon, the woman in charge of Frisk’s experimentation, had made a series of complex notations in her terminal on this aspect of Frisk’s development, and when Frisk stumbled across them while hacking her computer later, they tried to take it as a compliment. They were altogether happier with that being what their assigned handlers noticed, rather than any lurking intelligence behind every daily observation. 

But when they turned seven and were finally issued a Pip-Boy per Vault 100 regulation, Frisk had managed to do what their superiors had thought impossible. They had made contact with the outside world. 

This was thanks to a number of small clues left behind by their exiled family, some additional details considered unimportant by the research team themselves, and a handful of abilities lying dormant within Frisk. After a lifetime of brief interactions with people that towered over them and thought rather obviously _less_ of them, Frisk had a real conversation. It hadn’t mattered who was on the receiving end of the terminal, not really. 

They had cherished the mild rust and faint whir of the obviously secondhand machine strapped to their wrist from the moment they received it, but it meant only half so much as the blinking ‘Howdy!’ that flickered in the grime of the screen after they sent out that first message.

Now it seemed so obviously naive, to think that it didn’t matter who was waiting out there for them. How could anyone down in a Vault know what evil laid out under the cover of stars? Especially not someone who had spent a whole life sheltered and tested on. As they lay on familiar-but-foreign Vault pressed steel flooring, pain lancing their body and blood flowing past the hand pressed against their shoulder, they were just glad that they had bothered to make more than one friend. 

* * *

Friendship hadn’t so much been the goal of the Institute’s waiting ears, as Frisk had been on the Institute’s radar as a ‘person of interest’ since their birth in the depths of the earth in 2279. They were not aware of this investment in them initially, of course. And outside of the inconvenience caused to the leadership by having the first unscheduled birth in over half a century, Vault 100 was unaware of the outside interest in Frisk as well. The child was simply the payoff of a long-running series of infiltrations attempted by the Institute within Vaults that had opened to trade within the wasteland. 

The ill timing of their birth was not only to the frustration of Vault 100 leadership, but to those behind its culmination in the Institute as well. Many factors had failed to be properly accounted for, from the effect of cybernetic fertility enhancements compounded with the high-grade osmotic hormone control in Vault 100’s water supply, to the much simpler emotional element. Less than a year into her posting acceptance and marriage into Vault 100, Agent Berkana (as the Institute had dubbed her in your file) fell in love with her assigned marriage partner, and had engaged in the eager consummation of their arranged marriage. 

For most Vault 100 residents this would have been mildly taboo and frowned upon, especially as Berkana had been accepted in from outside the Vault which was a great honor to bestow an outsider. However, Agent Berkana’s entire mission had been to hack into the Vault terminal network, give birth to one or two children, and indoctrinate them into Institute ideals and Vault-Tec leadership. 

As though fertility and genetic chance were odds the Institute would leave in the air. 

Agent Berkana was unaffected by the various chemical blockers in the water, and the resulting child came to term with an almost tenacious growth. Frisk was born healthy to a fault, to loving parents and a deeply uncertain future. Within 36 hours of the birth, Agent Berkana and her Vault-born husband were exiled from Vault 100 and blacklisted by all trade caravans the Vault supported. The infant, despite their objections, remained below. 

Seven years had ticked by since then, in which the Institute hedged their bets on a possible sleeper agent rather than risking exposure to the Vault to retrieve Frisk. Berkana’s objections to the situation were noted in your official report but never heeded. She had since passed away, though it was unclear if that was from natural circumstances or some form of intervention on the Institute’s behalf. You certainly wouldn’t put it past them, though you had reasons to doubt. Namely the fact that your primary partner on ‘asset retrieval’ was none other than Frisk’s biological father, Adrien. 

He wasn’t with you out in the wasteland proper very often, but he had allied himself with the Institute as an informant since his emergence. He was a skilled electrician and computer repairman, a service that had made him an invaluable asset above-ground in a world where those skills were no longer commonplace. He was also a riot when you plied him out of his lab coat with enough liquor, determinedly invested in making himself a part of this case. You tried to be patient with him. Keyword: tried. 

* * *

“What do you mean, the rendezvous point has been ‘adjusted’ Adrien?” you exclaim, having come up from your hours spent underground in frustration only to receive a plethora of messages once you got back to your bunker. This far out from the Commonwealth you had come to rely upon a series of mishmashed safe zones, nowhere else offering any sense of comfort. 

The reply came through the wall speaker with a tinny ring that made your teeth hurt, “I mean exactly what I said. The kid has free will, I can’t do anything more than ping their Pip-Boy for location data and send along messages. They said they wanted to pick up a friend from another Vault before they came back west. It’s apparently the entire reason they left ahead of schedule.”

“What other Vault? I’m north of Corvega for fuck’s sake A. There _are_ no other Vaults within fifty miles that aren’t burnt out, sealed, or flooded.”

The delay in comms left you to look at your tattered area map in silence as you waited for Adrien to parse together the information he had available. Finally, the crackle of the speakers returned with Adrien sounding somewhat strained, “Alright, the latest pinged location data was from a few hours ago. Take down these coordinates: 43 North, 85 West. It seems like their Pip-Boy has sustained some sort of maintenance error, so it keeps cycling through error messaging when I try and open a messaging link. Last time I spoke to them, they were on their way to a different Vault.”

You took a moment to pin down the rough area on your map with the given data, about a two-hour trek on foot. Through Grand Rapids ruins was the quickest way if you were direct. You can’t imagine what that kind of trek had been like for the kid, fresh out of the tin can in the ground. Most sane wasters gave Rapids a wide berth due to the warring raider factions, but you also imagine the kid wouldn’t attract much attention. Unless someone caught sight of the telltale blue Vault Suit.

“Alright Adrien, I’ve got it on the map. I didn’t go through much on my trip to and from 100. Let me grab a few more supplies and I’ll move that way. I’ll have the kid reach out once we’ve made contact with one another. You know the drill.”

When his voice crackles back through the speaker, you’re pretty sure you can make out the emotional quaver that he’s fighting, “Be careful out there. You owe me too many caps to conveniently disappear into the north, and I don’t have the ammo to try and fish out your body with a _memento mori_ holotape attached.” 

“Thanks for the good luck, asshole. I’ll bring myself and your kid back in one piece. So send some better rations for the safe-houses along the way. Give Tam my best. Tracker Echo out.”

The speaker connection cut, you quickly grab your duffel and shove supplies for the two of you into it. You know better than to assume you can make it back here after crossing into any metro areas. It’s best not to burn through bunkers without discretion, and once you grab the kid from this unintended pit stop you want to make your way back west ASAP. 

You have too much time to yourself as you slither back out into the wastes from the concrete overpass and its bland protection, too many thoughts about the situation which go unsolicited. What’s worse for the kid in the long run? That you find their broken corpse somewhere in Grand Rapids and a junkie trying to pawn their Pip-Boy at a sealed Vault entrance is surely the _worst_ outcome, logistically speaking. But the idea that the kid had a friend out here, or down in another Vault, meant that the Institute hadn’t been alone with first contact. Adrien was a textbook example at times of the ignorance that could spring from Vault life, you hate to imagine the kind of advantage someone could take. 

This line of thought was obviously where Adrien’s thoughts had led, or something akin to them, which is what you imagine the emotional edge was related to. Instead, you pushed yourself towards the rational, you needed to make your way around the outer limits of the city and retrieve the Pip-Boy, if not the child attached to it. There was no sense prepping for a hunt as though it were inevitable. You hoped you had nothing to worry about, however much that felt like a lie. 

* * *

“Little one, can you see me?” came a soft, feminine voice to Frisk in the fog of unconsciousness. They attempted to push their lids open, which weighed about ten times what they normally seemed to. Through a wave of pain, they managed to slide their eyes open into a squint towards the voice. The lights were dim, and the only thing that Frisk could register was large and kind looking eyes before shutting their own and whimpering from the effort. 

“Oh no! Please do not let my appearance disturb you. If you’d like, I can step into the other room while you acclimate,” she blurted in quick response. Frisk shook their head and then clutched at it in the same motion, the flare of a migraine taking their skull in a vice grip. A high pitched electrical whine came from a nearby terminal and a light nearby flickered and burst. As the woman gave a gasp, Frisk brought up their other hand, only to note the lack of weight behind the motion. 

Their eyes flew open and they dropped their grasp from forehead to left wrist in a desperate movement to search for the Pip-Boy that should have been there. In the span of a few seconds, the migraine was forgotten as they registered both the absence of Pip-Boy and bodily injury, as well as taking in the full appearance of the woman across the room from them. Her eyes were still the first thing that they noticed, wide and almond and watery. But their place on her face was distorted by the width and breadth of an elongated snout and a downy coat of fur, complemented by a matching set of draped ears and small inset horns on her forehead. 

They each warily regarded the other, Frisk’s eyes landing on the matching dirty blue of the mutant woman’s Vault suit to their own. Except that hers had been embroidered with tiny flowers in patchwork designs. Their eyes met cautiously across the dingy lab room and the electric pitch returned manifold, before the overhead light shattered and blanketed the room in shards of glass, silence, and darkness.

**Notes for the Chapter:**

> Well, looks like the world is burning down. Have another chapter. I'm also in the market for semi-comprehensive feedback if anyone has the free time to beta read. Thanks for all the love from last time!


	3. Chapter 3

Was there anything in the wasteland as glorious as the ingenuity in Vault-Tec’s audacity? You sincerely doubted it, given the amount of your time they had burned through in the last two weeks. You’d spent _twelve hours_ crawling through northern Rapids suburbs for any hint of Vault Pre-War propaganda only to learn from a junkie that Vault 66 was an experimental, _supposedly_ unoccupied, corporate vault. 

You moved out the next morning to the low, sluggish sunrise of the Midwest marsh. Three days of Michigan mugginess in mid-Spring left you feeling grimy and spent before the day began, but you moved with renewed purpose. Once a destination was in mind, suddenly the hours didn’t feel like as much of a waste. Once you’d known where to apply pressure, the rest of the information emerged with relative ease. It helped that you were dressed as one of the most well-regarded merc-groups out of New Corvega’s loose urban sprawl, the Venerie. 

Their captain, Alice Morik, had outfitted you as a thank you note of sorts after an impromptu rescue sometime last year. Alice was good enough people, considering she was wasteland born and bred. Knew enough details of the kind of life you lived and what a useful tool disguise could be. Not a gift given lightly, or one wasted on you. The navy combat armor was well-loved over your time with it. It was modular, and therefore cheaper to repair and upgrade than most of your typical flak-dressing. The only bitch of the thing was getting ahold of matching paint. 

So with pressure duly applied, you moved towards the suburban outcroppings north of Grand Rapids and the hospital in which Blythe Genetics had organized a corporate post-apocalyptic retreat. You stayed on edge through the route, the area wasn’t overly encumbered with Super Mutant activity but the hulks tended to burrow into hospitals with almost annoying predictability. It was a hard lesson for some to learn, one that had led to a number of premature deaths in the wastes. 

Regardless of your wariness, the Rockford suburbs were quiet and stood undisturbed in defiance of the quickening daylight. You got comfortable and kept watch over the entrance for nearly four hours before you decided to press on with scouting. There was half a mile surrounding the low three-story building that was clear of decent tree-cover, or really any non-flammable cover at all. You wanted to be sure that if you were in a firefight that it wasn’t just you and the protection of an overturned Blitz sedan. After so long without movement, you’d take the risk over the boredom. 

* * *

Greeted by the flickering lights of ‘Blythe Genetic: Rockford Campus Hospital’ you made a note to dismantle any non-Vault bound power supplies. The cost of this unexpected excursion could be further mitigated by the oldest and most traditional jobs of the wasteland: scrapping. 

You push in through the front door and immediately are filled with both relief and a knot of dread. It is obvious that no one has been through here before you for a long, long time. Unfortunately, the reason for this is apparent, you have to kick the lobby door open far enough to accommodate you through the clog of partially mummified bodies. There is glass scattered amongst the dust and grime from where the windows blew in. Safety threading holding enough of it in that they are still there, forever blown in by the crushing atomic heat 200 years prior. 

You’re as stealthy as you can manage, but you have to sidestep bones or glass constantly. It’s just as bad down one of the halls leading off the main lobby, and you realize with this observation that they must have been queued in line for _something_. It’s a mild relief over the potential of them having been arranged, but it begs the question of _what_ , exactly, they had been waiting for at the end of the world. The bombs dropped on the east coast almost forty minutes before the one dropped in Detroit, these people would’ve known the potentials of waiting. 

The slick dread curls back through your torso, and you follow the line visually as it skirts past reception. Trudging slowly, to keep from making too much noise, you walk to the door the line had been moving forward through. Sure enough, following your hunch, the line of bodies continues onward down a flight of stairs, albeit somewhat better preserved as they descend. You try to look up, avoid lingering on the horror that must have been these people's last moments. You know as you descend into the sub-floor levels that this line was for the vault, those who’d had their fate sealed when the bombs dropped were likely employees from the hospital. 

As you take a corner, the tile suddenly sloped downward towards the far end of the room like an amphitheater. Standing before you, inset into the hospital's painted cinder block walls is the bulkhead door of the vault entrance. The exterior painting job was never finished. Despite that, there are white-and-rust numbers across the front labeling it: ‘Vault 66’. 

You look it over thoroughly, a somewhat persistent sense of paranoia in the back of your mind. It’s a small detail, but your mind refuses to let it go. You’re almost certain that corporate vaults don’t have numbers. It wasn’t a certainty, you didn't stay up-to-date on vault lore. A part of you knew you could ask Adrian and he’d have a more definitive answer. A fat lot of good he did you, 500 miles away and tucked safely underground, where he was comfortable. 

So far you’d been trudging onward within the vanity of curiosity, there were more than enough red flags on this case for you to know pride was a major factor in its ongoing ‘open investigation’ status. Even if the hospital looked undisturbed, there was the question of why more of the corpses weren’t feral ghouls, or where Frisk was if they hadn’t come through this way. But underneath it, there was also the burning satisfaction of having found the Vault, especially one that wasn’t supposed to exist. 

Initially, that was going to be enough for you. You’d laid eyes on the damn thing, could confirm that the kid hadn’t seen fit to hole up in the company of corpses, and would move along. But then you realized it was hours to the nearest safehouse, operating miles outside of common territory the way that you were. Surely the easiest way to sate everyone's curiosity in the quickest manner possible would be to reach out to Adrian via the Overseer’s terminal? It would mean you could potentially get a ping on Frisk’s Pip-Boy location, cataloging the details of this vault for a future expedition. 

You weigh the options, but curiosity killed the cat and it demanded satisfaction before you could turn back. Silently hoping that attitude wouldn’t damn you to an early grave, you holster your carbine and pull out a modified pulse mine. A night you should have spent sleeping on the road instead had been wasted tinkering with it, anticipating where you’d be going. The kind of barriers you might be faced with in the name of breaching a vault.

There was an emergency maintenance hatch in the drainage piping you found after about fifteen minutes of crawling around in the grime. It would suffice, though you had hoped for a more accommodating side entry door. Anything that gave a softer entryway than the actual Vault 66 bulkhead was acceptable, but this cramped option meant you’d take some knocks in the process. You rubbed the edge of the pulse mine and then drop yourself as deftly down the grate as you could, pulling the iron hatch loosely back over the entry above. 

The short metal ladder provides a cool headrest as you steel yourself in the shadows for the task ahead of you. Rolling your shoulders, you slip a small crowbar out from a loop on your bag and slide on a pair of goggles, the light attached flicking on as you adjust them to your face. Adjusting to the sudden influx of visibility, you adjusted your stance to suit the new loadout. The pulse mine began to lightly vibrate in your hands as you flicked a switch on the side, and you started a slow count as you move into the tunnel proper. 

After a few feet you come to the drain entry below the vault door, likely configured to work with the initial grid and layout of the hospital above. A moment's listening confirms your suspicions were correct and the mine in your hands will fulfill its intended purpose. There is a distinct and steady whir of powered systems beyond the metal walls nearest it. You take a beat to affix the mine to the top right corner of the door with duct tape, and another to pull a handkerchief out of a pocket inside your armor. 

Knocking the timer into gear, you begin to move backward rapidly as the warning chimes commenced counting down, pushing the folded cloth into your mouth and between your teeth. The blast to follow is inevitable, but not terribly damaging to organic systems in practice. Despite logically knowing this, you cannot help but brace yourself and clench the cloth between your teeth. The shockwave rolls through you with a painful full-body muscle spasm, the jerking force of an involuntary twitch. 

You blink away wet eyes, and your ears are now ringing with tinnitus loudly enough to make observing the sounds beyond impossible for several minutes. Gathering your wits in the aftershocked silence of mild brain damage, you leverage the crowbar into place and put all of your strength into maneuvering the vent cover upward. It is not a push in vain, because although you cannot hear it give way, you feel the cover slide up with ease once you push it past two inches inward. 

Practicality weighing out in the long run, you choose to leave your crowbar behind in the shaft, propped in such a way as to give a guaranteed exit point. You briefly fret mentally about needing to leave the shaft propped open after you leave, but crowbars could be salvaged with relative ease down the line if you needed. 

Shimmying through the remaining drain pipe, you find an entry under the vault lining further back than you would have expected. You chalk it up to the pre-existing assets underneath the hospital, fumbling the entry hatch open and hauling yourself up into the stale air from decades past. As you slide the reciprocate door open into the vault entry bay you are not greeted by the expected darkness, but rather a dim red glow throughout the room. You spy a turret in the far corner, more advanced than you could have anticipated, and trained on you already, though remaining non-hostile. 

Breathing slowly and moving carefully, you make your way around the room and take stock of the surroundings. A terminal is locked behind a passcode wall that you’re too addled to focus your eyes on and solve, but you get the gist of a red alert. Another turret watches you from the opposite corner, and the low vibration of the generators thrumming below your feet gives you the distinct idea that they may not be the only two. Still, though, you count yourself lucky to have caught this moment to breathe now that you’re inside. You had expected worse.

You’ve become distinctly aware of the potential brain damage you sustained given your proximity to the pulse shockwave earlier. It behooves you to slide out of the main chamber and move somewhat further into the unplumbed depths, if for no other reason than that the edge of nausea has inflamed a sense of urgency. The small sampling of vaults you’d been in over your life let you know that they kept their business ends close to the front. The Overseer was part of that business often enough to merit quarters or an office of some variety near the surface.

Some fumbling through the unfamiliar metal halls leads you in a circle, briefly, before rewarding further exploration with a vague bedchamber and office suite, along with a distinct bathroom-esque chamber in the open room beyond. 

Moving into the room you're not as rushed or careless as you could be, still armed and with the illusion of awareness schooled onto your features. But as you cross the threshold of the bathroom and see it unoccupied by anyone living or otherwise, you rush forward towards the basin of the shower and retch. The contents of your morning take a violent rebellion against your choice in vault breach, and the consequences mean that your inner ear has taken a hard hit.

Relieved of the most immediate of bodily demands, you push yourself up and essentially into the sink basin as you turn the faucet handle to test the plumbing. Ice cold, freshwater greets you and you groan into it and slosh it onto your face further, rinsing your mouth out. Rare were opportunities to wastewater, even in places with a purifier on hand. The urge to forget yourself was briefly overwhelming, but you rinse your mouth out again and push yourself back to a righted position. Your head swims in a sea of fuzz, torn between feeling numb or feeling like shit, piercing your peace and happiness with a ringing noise. 

You’re lost in the sensation of water on your hands when the unnerving sensation of being watched snaps you coldly back to the present moment. You struggle to focus correctly as your view shifts into the grimy and broken mirror ahead, but you can make out movement. Only as you move to reaction do you become aware of how slow your response time has become, unaware of even having put down your gun. A cold slice of sharp metal pricks dangerously close across the front of your abdomen, pricking up into a point along your ribs. 

Your attacker's other hand, wiry and deceptively strong for something rail-thin, grabs around your throat harshly and drags you back against them. The struggle is too sudden to be loud, and once they have you trapped against them and threatened into stillness they make no further move. You try to refocus your eyes in the mirror again to ascertain the threat of the situation. What you see doesn’t hold up well with common knowledge or logic. 

In the mirror, you lock eyes with your adversary. It’s too dim for you to tell much about your features outside of your own familiarity with them, but the grip locking you into place is very much that of a ghoul man. A man who gripped your throat with pointed, boney fingers and tendons hardened by time, but also a man that was _glowing blue_. His eyes were pricks of cyan light against the dim background, his features away from the glowing musculature remaining obscured. As the two of you locked eyes in the terror and adrenaline of close-quarters combat, you are urged out of your surprise by the rasp of his voice, “it’s rude to stare, you know.”

An impulsive flight response rises up within you, his voice edging a tone of ferality that you’ve never heard a sentient ghoul skirt before. You move to jerk away suddenly, towards your weapon, as his grip gives a modicum of slack. In your favor, you call the mild bluff, he doesn’t push forward with the knife and kill you. But you don’t account for what you can’t know, and the rush pushes his grip against your neck into the equation of your fall. You feel a dull, distancing throb that you file away, most likely as your head hitting the counter alongside the sink. 

Darkness, and the blasted ringing of tinnitus, rush up to meet you at the threshold of your consciousness. You hold on as long as you can manage, unhappy to be left somewhere so prone. But this isn’t pain you can process properly, and at the moment the overwhelming urge to just ‘let go’ interferes with any objections about your possible cannibalization. Some long-dead part of you chastises yourself for the automatic assumption that the ghoul would eat you. The rest of you reconciles that _all_ of you is probably long-dead, and cannibalism looked like a healthy middle ground for bad ending options. 

You lose yourself to darkness moments later, among the distant sensations of your body being moved. 

**Notes for the Chapter:**

> I hope this update finds you safe! We manage to avert my favorite bad habit here, POV breaks! That and the introduction of the other main character and we start what some may arguably call a story. As a note of clarity, I am writing this the way I like to read reader-insert fiction: no name placeholders (I find them jarring), and very vague descriptions at best. Sometimes this will be a bit convoluted to describe. Apologies in advance, but it's my preferred flavor of escapism. Stay well guys!


	4. Chapter 4

You wake up to the soft white noise of static, which periodically garbles in unpleasant response to some form of interference. The dim halogen lights lining the ceiling hurt your eyes as you stir, and you sit up and duck your face into your hands with a low groan as you adjust. The metallic wall paneling confirmed you were still in a Vault, for what little that was worth. 

Standing is a mistake, you realize immediately after doing so. While you don’t _quite_ topple over again, the sharp pitch in your vision makes you grasp the wall for support. A moment later you lean your shoulder and head against it too, the cold thrum of the metal providing a mild balm to the ache buried beneath your eyelids and along your brow. 

Strength and willpower thus gathered, you soldier onward with your attempt at movement. A part of you wants to call it a breakout, a getaway from whatever or whoever made the mistake of crossing you. But you’re too disoriented, likely suffering from a concussion and almost half a mile underground, to really foster much in that notion. Your cards have fallen, now you have to play according to the hand on the table, which leaves a lot to be desired. You’re pretty sure you’ve been in worse situations, but you aren’t having much luck remembering when exactly.

The room is plain and clean, but it gives you the feel of a holding cell in how clinical and reserved it seems. Despite being set up to simulate a residence, it’s hard to believe that anyone actually lives here. The static comes from the only feature inset along the room walls, a small screen panel on the far end of the room that has several hairline fractures running across its face. Between the breaks, the screen is still trying to broadcast its message, but all that comes through is the occasional ghostly motion of a figure. 

The speakers seem to have also been damaged with whatever impacted the screen, but you can’t see them beyond the grills built into the walls next to it. You move away after coming to the conclusion that you can’t get much out of it, mildly bothered by the unpredictable intervals in which the gargling noise of white snow unmuted itself. 

All-in-all, it’s a lackluster tour. The metal bed and its frame make up the only bulk of furniture in the room, and neither of the doors present in the room respond to input commands. You sit, leaning your head against the wall again for relief, and gather your thoughts as you’re left to your own devices. 

Time isn’t terribly obvious in its passage to you, and briefly, you wonder at how long you were out or how long it might take before Adrian or the Institute sent a follow-up team in. Resources this far out of the Commonwealth were thin at best.

It’s been as close to half an hour as you can approximate when you hear something through the wall you’re leaned against. It’s a strange difference, not footsteps or shuffling like you might’ve expected, but a sound like metal groaning as it stretches. The noise burrows through the wall upward and past where you’re sitting and seems to arch overhead and across the ceiling. The lights flicker with the strain on them, but they don’t go out. 

When the strain of metal stops, however, it’s almost more disconcerting. In moments, the screen to the side of the room flickers out entirely after another burst of static. It’s possibly a concussion or even an isolation based hallucination, you tell yourself, but behind the glass of the screen, you see _movement_. 

Coils of… _something_ roil just behind the opaque glass, accompanied by a new sound of strain a moment later. The screen, already broken, pops and cracks for a few moments before it shatters outward. In the silence that swallows the room afterward, you stare in a combination of fascination, confusion, and horror as a thin, leafy vine emerges into the room from behind. 

It moves in a snake-like, slithering manner out from the entry point it’s made, stopping after it enters roughly a foot in and angling towards the lights. Things go still for a moment afterward, there is no movement as you stare openly at the bizarre aftermath of this occurrence, but then another small groan of protest murmurs through the metal walls again. The vine twists back in on itself towards the wall, contorting, and when it stretches back out to the center of the room there is a small bud present on the end. Without waiting, it bursts to open into a bright yellow flower. 

You stay perfectly still on the edge of the bed for a long minute afterward, waiting for something, _anything_ , to happen. The vine sways a bit, back and forth as if in a gentle, nonexistent breeze, but makes no further motions that you can detect. Getting up to investigate, it strikes you how little you have to work with given this development. Plants in general, let alone flowers, weren’t commonplace along the remains of the east coast, so recent familiarity isn’t going to be the ace up your sleeve. 

The gentle sway continues as you approach cautiously, and it might be the paranoia and the slight kick of adrenaline, but it seems to sway in time the heartbeat that's pounding in your ears. It’s by far the most vibrant thing you’ve seen in a long time, let alone in the barren landscape that makes up these quarters. Given how it arrived, however, you can’t bring yourself to come within more than a meter of it. The petals are thick and waxy, a shade of yellow that you haven’t seen since your childhood out west unless you started counting pre-war posters. The longer you stare at it, the more details about it you seem to notice: the green of the vine is intersected with red, spidering lines, it’s leaves have a stunning whirled pattern to them, and it is _almost certainly_ moving in time to your heartbeat. 

You become so caught up in these observations that you struggle to look away from how pristine it is. All you can think about is how you’d _never_ find anything so beautiful or alive in the wasteland is above. Surely it must be a large plant if it’s found its way through the ventilation shafts, it couldn’t hurt to just hold on to _just_ this one flower so you’d have proof that it existed at all…

The light above flickers out and plunges you into darkness and you suddenly become aware of sound behind you, your arm stretching ahead of you, reaching out without conscious volition into the air in front of you. Movement akin to metal rattling can be heard above you and through the wall again suddenly, and you see the shadow of the vine jerk back and disappear into the void that had been the monitor. A soft blue glow has filled the room in the absence of the halogen lights above, and you turn to face the source of the interruption. 

As you take in your captor again, you realize that you aren’t fully in possession of your faculties. A false calm pervades your senses, each blink peeling away fractions of a fugue you hadn’t realized was overtaking you. The hand that had reached out itches and burns as you fight an irrational frustration that threatens to fill you from the withdrawal of the flower. A stony silence fills the space between you, the glowing one regarding you passively as you regain your bearings. 

After a rough minute has passed, he reaches over to flick the overhead lights back on. You can see the twist of glowing muscle down his neck into his left deltoid, as well as the fact that along the left side of his face the jawbone has been laid bare. You shudder to imagine what could have dealt so much damage as to lacerate off a portion of his face. He curses under his breath as you observe, and you glace up to realize that the light above isn’t responding to the clicks he’s orchestrating along the wall. 

Soft cyan eyes land on you again, seeming to give you a once over despite the dark, and he says in a low voice, “we should leaf, i’m not sure when it’ll try to come back.”

He turns away from you, seeming unconcerned with any threat you may pose to his unaware retreat, but leaves the door open. You hear the ghost of a chuckle follow him and do a small double-take, did he just make a shitty _joke_?

You follow, slowly becoming more steeped in the awareness that you feel like absolute garbage, probably from the combination of a probable concussion and _whatever_ that whole deal with the flower had been. _No wonder he wasn’t concerned_ , you think to yourself darkly. If you looked half as bad as you felt, even in this darkness, then you wouldn’t appear to be a threat at all. So, lamely, and without much in the way of options, you forge onward behind him.

* * *

The Vault around you appears to be abandoned, all of the lighting in the hall is dim and the only sounds you can make out in the distance are the low murmurs of distant machinery. Despite this, it seems well maintained. There is light dust on the edges of panels you pass if you look for it, but for the most part, you just have the pervasive feeling of emptiness inside space that had obviously been meant for more.

Seeming to read your thoughts as you observe another empty offshoot corridor, your ‘guide’ speaks up, “the residents are on a different sub-floor, you can stop craning your neck to try and catch a glimpse of someone.”

While the answer doesn’t satisfy, you follow along with your expression and curiosity somewhat more schooled. There is a lot you needed to try to glean from this individual, and it’d be for the best if you could get it through diplomacy or coercion rather than force. If you knew where he’d stashed your things, you might even be able to make a bit of proper progress toward the real reason you were here. 

He leads you into what appears to be, for all intents and purposes, a rather generic office. The only difference you can tell in this one from the handful of others you passed along the way, is that there is a door along the other wall and a window with metal shutters shut next to it. He seems to relax marginally as the door slides closed and a chime sounds behind you, and he motions towards the chair facing the desk. You hesitate, but he sits down with an air of distraction and clicks a button on the keyboard a few times before looking back at you expectantly. 

“Do you mind if I turn on the light?” you say, motioning to the switch right of the door, as though that was the concern keeping you on your feet. In reality, you were tired of squinting at everything in this pervasive half-light. Did they not believe in using anything outside of emergency lighting, or did he simply not need light to see? 

The ghoul gives a slow blink, as if mildly surprised, but you catch a mild huff of breath and gather that light must not be a commonly used utility for him. _T_ _he latter then._ It takes a beat for a reply, but he nods before glancing back to the screen in front of him. 

Pushing the button once, the dimmest setting of the light flickers on above. Your finger hovers over the switch, as the idea of clicking the brightness up crosses your mind. Restraint creeps in, the desire to avoid inflaming frustrations when you don’t know what you’re up against stills your hand. 

As you turn back to the desk, you can’t help the sharp and pained hiss of air through your teeth. He's striking to look at in profile, pale blue eyes alight and observant, pinning you in place. For all that he has an expressive face, he's possibly the most _inhuman_ looking ghoul you've encountered. At least, of those with sentience. You can't help but to be mildly horrified by just how very _damaged_ he looks, despite his mouth ( _lips? jaw? teeth?_ ) pulling in a sardonic smirk. You can feel heat color your face as you muster up enough awareness to be embarrassed by your reaction. 

Taking in these reactions, the smirk pulls a bit broader as he introduces himself, "they aren't so great with manners up top, are they, human? i'm sans. take a seat, and you just might manage to avoid the regret of stumbling your way down here."

**Notes for the Chapter:**

> What have you fallen into? Tsk.


	5. Chapter 5

Tamara Boles had managed to use up all of her goodwill within the Institute roughly two years ago, and burning the candle at both ends in order to stay alive ever since. She was confident enough in her position as of late, comfortable with the loyalties of Adrien, which included you by extension. But it didn’t mean that she was willing to table some of that confidence in order to rescue your corpse. 

The dust was still settling from their most recent row. Adrien was out, pacing and having a cigarette. _I just never pegged you for the type to give up, Tam._ The fucker knew exactly what would eat at her ego. Why bother to inflame her pity towards him, when it was so easy to make her blame herself instead?

It wasn’t that she wanted to leave you to die ( _i_ _f you weren’t dead already_ ), but the situation was precarious for everyone involved. You ( _or more likely your body_ ) were 500 miles away. The risks of sending a live agent into Vault 100 were problematic for maintaining a low profile. Four days was a long time to sit in the dark. A lot of caps, a lot of time. They were all good reasons to leave. Each day that went by made the call back to the Director a harder one to seem assured of.

Despite Adrien’s anger, Tamara had done what she could to keep the assignment open. She’d bought all of you an extra 72-hours before they had to pack it up and call it a day, neatly tabling this to never be discussed again. It was how the Institute handles all of its longshot failures. She’d made her peace. Her grief over you and the project had been respectfully filed away until she had a spare moment to handle them later. Years of trained compartmentalizing meant later didn’t show up very often. 

Lighting a cigarette of her own, she looks over the communications array they’ve been bunkered with, willing it to show some sign of life. It doesn’t, though the heavy silence of the small garage seems to close in around her. She sighs and takes a pensive drag, coming to the conclusion that they weren’t meant to succeed here. The only real question is who the lesson was for, her or Adrien? _Maybe both of them_. 

Shame that you should have to be the one caught in the crossfire, but supposedly you’d been made aware of the risks. Tam stubbed out the rest of the butt, pushing herself up and checking the time. _65 hours left._

* * *

You take a seat on the faded office chair opposite Sans. Deciding it’s best to acknowledge your curiosity and observation outright, you don’t make a move to mask the roaming scrutiny that you’re putting him under as you sit. To his credit, he seems just as curious about you. There’s an odd mutual silence that stretches between the two of you as you each take in the features of the other. 

You know from following him through the hallways that he stands a little shorter than you. The difference isn’t as apparent while you sit, placing you at eye level across from him. Electric blue eyes meet yours with flawless clarity and focus, the sclera around his pupils and irises a dark backdrop of ominous, inky black. In the patches of smaller muscles near his eyes, you can see a trail of vibrant neon muscles intersecting to join the heavily glowing ones along the right of his spine and neck. Another thicker rope of glowing muscle twists down the left arm into the hand that gestured for you to sit. 

His left hand shares the grievous damages present on his face, as does a portion of his neck and shoulder. Which is to say that the skin and muscle structure is completely worn away in some areas. It leaves his skeleton and a lattice of fine, translucent cyan musculature exposed in a haunting appearance. Much of his expression was characterized by the pull of his grin and the complimentary depth lent to his inhuman eyes from rather expressive brow movements. A fact that pulled him out of the realm of horrifying and into a strange grey area. It’s also nothing you’ve ever seen in the progression of ghoulification for the few you’ve witnessed in your years. 

The mutual silence is broken by him looking away first, brow furrowing together as he seems to formulate where to start. You decide to act first, “I didn’t know there were any occupants in the Vault when I broke in. I just needed to use the Overseer’s terminal to send a message.”

He glances back to you as you speak, scrutinizing you as you meet his eyes. A beat passes and he nods, but he doesn’t immediately respond. His skeletal hand rubs against his face and you try to mask how very fascinating _that_ is. A smirk pulls his mouth quietly, but he seems to think better of commenting on your gaze. Instead, he lets out a soft sigh, “it’s almost worse that you seem like you’re honest. cause that just means that i’m the asshole. i can’t let you send a message. hell, i’m not even sure if you _can_ leave.” 

Whoa. _What?_ No, that wasn’t going to work for you _at all_. You take a moment to have a brief, diplomatic breakdown with yourself about how to respond. Diplomacy seems to be getting a response, no sense completely throwing it out the window at the first sign of difficulty. “Listen, I get that you might have put in a lot of effort to appear like you, well, aren’t here. But I am happy to do whatever you might need in order to vouch for my _complete_ discretion.”

Sans watches the hints of panic and deliberation as they cross your face, and for the first time since he came into the room and interrupted the flower… _thing_ , he frowns a bit. The mild panicky edge in your voice settles in an uneasy break between you as he weighs his next words. 

“there are… layers to the issue. i don’t think i’m the best person to explain it to you.” He leaves off and doesn’t elaborate further for the moment, and you aren’t sure if it’s something you can pry into safely. It’s not like you know anyone else here. You both seem aware of the discomfort in the silence that now spans between you, but it grows regardless of its perception. 

Sans’ eyes end up flicking to the monitor on the desk, but whatever he sees there catches his attention and he does a bit of a double-take to investigate further. You’re left to observe him again briefly, reflecting on what he’s said as he taps on the keyboard in front of him. His eyes follow the progress of something on-screen, and it’s as you watch the glow of his irises track it that you become aware of the absence of radiation sickness. He may look the part of a ghoul, but whatever vat he’d been dunked in wasn’t one of standard nuclear goop. _What if all the residents are ghouls? That could explain the hesitance to let the word get out if this place_ ** _is_ **_a sanctuary. Doesn’t exactly explain the flower though._

After another moment of sitting and letting him watch the screen, he turns back to you with a brow cocked in inquiry, “no chance that this is what you’re after, is there?” 

The bottom of the monitor makes an unsightly groan as he shifts in your direction. You rise up to lean over the desk and make the view a little easier on the both of you, catching a grid of security camera footage in grainy black and white. In the top left is the only view you have any recognition of, the dim blow of the vault entryway and the floor panel still ajar where you had maneuvered in. Several spots on the grid are blacked out, but he had one highlighted so that it remains larger on the screen. 

The camera’s angle is pitched a bit low, it seems to catch a junction between a large corridor. A moment after Sans hits a button and the clock starts ticking again, a vent you’d barely registered drops to the ground. Instead of the anticipated vine, a small head pops out and glances in either direction. 

“Is that…” you start to ask, but the words fade as the tape plays on and you watch the figure you think might be Frisk drop a cord from the vent and begin to shimmy down it. Given that it’s in greyscale, you can't tell much. If they are still in their Vault suit, they now have a massive striped sweater over it. After getting to the bottom of the rope and tugging the length down, they wrap it around their arm to take with them. They move to make their way down the hall, but not before they lay a hand on the door that’s closed off next to the vent. Frisk’s hand lingers on the door for a beat too long to be casual, and then they look up at the camera recording with eerie certainty before the camera in question fills with static.

You look back to Sans, even more unnerved by the lack of radiation given your proximity, only to find that he’s leaned back and watching you with a tight expression. You reach up and rub your brow in exasperation, though you get a taste of your own medicine when he watches your motions with just as much poorly veiled curiosity. After a moment to process some of what all this information means, you sigh and meet his gaze, “Yes, unfortunately. _They_ are exactly what I’m after.”

**Notes for the Chapter:**

> I'd like to apologize to those who have been waiting between the last chapter and this current one. I, unfortunately, have had some major lifestyle changes in my work/life balance since Coronavirus became the center-stage topic. My work has contracted out for some tertiary medical support and supply, which has meant, unlike many people during this quarantine, I have been blessed and cursed with a workload that just won't quit. Updates may be a little more sporadic in the next few weeks, but it shouldn't end up this far off again. Regardless of the wait, I hope you enjoy it! Your thoughts and feedback are appreciated!
> 
> [09/20]- Time would find that I was a filthy liar. To all those who are patient enough to reread or resume this story, my sincerest apologies. I'd like to blame the world, but I'm mostly at fault.


	6. Chapter 6

“I need you to understand, I can hurt you worse than I already have,” came the low, dark voice from the back of Frisk’s mind. Their frown was the only response given, instead focusing on scooting forward in the tight metal enclosure of the ventilation shaft. They were sturdy, warm, and not all that dissimilar to the vents that had connected the essential networks of Vault 100.

A headache began to build behind Frisk’s right eye, the strain of trying to keep the voice at bay beginning to cause negative neural feedback. They couldn’t keep the voice from speaking, but it seemed it was possible to keep it from calling up visions. As they elbowed and grunted their way around a corner, they relieved some of the tension building up by focusing forwards. A grate was blocking their path now, roughly a yard away. The metal groaned and echoed with a building of noise as vibrations grew in intensity in the small shaft. There was a clang as the grate popped from its welded position and clattered further down the narrow metal corridor.

Wiping the sweat now beading above their eyebrows, Frisk assures that all of the supplies they took with them from Toriel’s sector are still secure before continuing to make the achingly slow progress forward. _Not if I don’t let you_. They finally think in reply, knowing the unfamiliar weight in the back of their mind was still listening.

* * *

Sans meets your eyes again before letting out a raspy sigh, “this is gonna be a problem then.”

You shift your feet, trying to quickly regain your understanding of the situation in light of knowing that Frisk _is_ here now. A frown pulls at your lips automatically from the sudden negative response, “Why don’t we both get on the same page before we start adding problems to the pile, huh?” 

It comes out a little closer to your frustration than the casual tone that you were going for, but if he takes offense he doesn’t show it in any way you can register. Instead, he gives a raspy chuckle and gestures for you to sit back down, “it’s not the first time i’ve seen the kid clambering around, they aren’t exactly subtle with the racket that they make. but it did make for a convenient method in confirming my suspicions about you, so i’ll have to add a ‘thanks’ about the timing on when i formally introduce myself to them later.” 

He leaves off for a second to turn his attention back to the computer, though it doesn’t seem to be related and he doesn’t offer for you to look this time. When he turns back to you, you swear that he’s taken on more of a glow, but he chooses to continue his previous train of thought. 

“we’re only aware of the surface in a fictive sort of sense, in all my time down here, no one has come down from the surface. now, you’ll be the second one this month. i’m part of vault security, so that means you fall into my jurisdiction. suddenly my job has gone from borderline nonexistent to mildly essential, and you don’t even know what you’ve managed to fall into. so, to start getting you as close as i can manage to wherever the same page between us might be… i’m sans, vault security. this is vault 66, and up until last week, there were no humans here.”

It’s not much in the way of new information, but it gives you enough context to be appreciative. Obviously there was a basic understanding of ghoulism if they recognized themselves as non-human, but the idea of explaining the surface to someone without experience made you uncomfortable. If they only had access to pre-War archived information, who knew if he’d believe the picture that you’d paint?

You introduce yourself in turn, “I’m part of a group known as the Venerie on the surface, hired by the child’s father to retrieve them from a... delicate situation in another vault. By the time I arrived, they had left of their own volition and made their way here. I’ve spent days trying specifically to figure out where ‘here’ was. You guys haven’t had visitors before because your vault is really, _really_ fucking difficult to find. Apparently the rumors of a corporate vault in the area were never substantial or promising enough for any of the local raider groups to thoroughly investigate.”

Sans’ fluorescent eyes flick back and forth between you and the monitor as you speak, but he remains attentive. Hopefully, it was enough of the truth interspersed to allow the rest to sound genuine. 

“so if you had such a hard time finding this place, why was the kid able to slip in through a supposedly non-existent back door?” Sans asks. 

“That is a question I think we both want the answer to. I have reason to believe that they were previously in contact with someone in your vault.”

“that’s gonna be a problem, then. theoretically, contact with the outside should be impossible for the residents of 66, even our ‘overseer’. so we’re dealing with a breach of lock-down on a rather unprecedented level. that’s all i can offer you right now.”

You’re quiet for a moment, gathering the will to speak calmly, “What do you mean, contact outside of the vault is impossible for residents?”

His gaze slides back into unnerving eye contact for a long moment, “like i said, until last week there were no humans in vault 66.”

It still takes you a beat to piece together, but suddenly the security measures in the front of the vault click together and the situation makes more sense. Vault-Tec had pre-programmed measures in place to quarantine in case of experimental breakdowns. If everyone in the vault _was_ a ghoul now, then they were trapped by the same system that was supposed to keep them safe all these years. The hope of having any kind of level for the playing field tastes sweet in the back of your throat.

“Then there’s a chance we could reach a mutually beneficial arrangement. You help me find Frisk and talk them around, and I can help you guys get a taste of the outside world. Or just hit the kill switch on your lock-down. _If_ that’s what you want,” you say, having realized halfway through your offer that they might have preferred their isolation from the world above.

Sans seems to weigh this option, “i’d be lying to ya if i said that didn’t sound appealing. but i’m mostly concerned for the kid. seems to me like they might not know you’re coming for them, and if that’s the case it would be irresponsible of me to just pack them along with you. if all the cards fall right, it does sound like the best of both worlds. heh, _both worlds_. but i’m not gonna take that choice away from the kid. when it’s all said and done, if they want to go with you and you want to open the vault up, i won’t complain about how it worked out.”

You blink. It was a pleasantly rational position to take, and it notched your opinion of him up just a bit. You hadn't been sure how ‘bounty hunter for kid’ might land with your audience. That still meant you had to talk with Frisk, but you’d been planning on that from the start. It wasn’t like Adrian would forgive you if you kidnapped his kid and put them through even _more_ unnecessary trauma.

The smile you give him is about as genuine as you let yourself get with strangers, “I can work with that. Frisk was originally aware of the plan if that helps you feel any better about it. All of this effort has been in the hope that I could get a heart-to-heart about what they’ve been through. From what I know their last experience with vault life wasn’t stellar, so I’m just surprised they came down here of their own volition.”

“you and me both,” Sans says, and it seems to signal a nonverbal truce between the two of you. He sighs into a stretch, and you watch as he rolls his shoulders and stands up, “well the next course of action for me would be to get you checked in and introduced to the overseer. then we can get the head of security to help us track the kid down. congratulations, you get to be vault 66’s first _official_ visitor.”

“Do I get a door prize?” you ask a bit cheekily.

“no, but i’ll see what we can do about a window prize instead,” he replies with a wink.

You stand to follow him, a half-hearted and confused smile touching your features. He was really committed to the idea of the jokes, it didn’t seem to factor in with your presence at all. You move back into the eerily empty hallways, the uneasy silence seeming more oppressive in the larger space. 

As you take the first turn he points out, he decides to bridge the gap, “you’re being an awfully good sport about this whole thing. i expected more in the way of threats or violence. especially after our first meeting. now i keep meaning to apologize about that, but you haven’t even brought it up.”

You shrug, “If you want the honest answer, I can recognize when I’m at a disadvantage. My goal is to find Frisk, and to reach back out to their father. You have my weapons, and I don’t know the way out. I’m a merc, and competently strong, but I’ve fought ghouls like you before and you’d likely outmatch me. You’ve got the cards here, and call me pragmatic, but I’m not going to hate you for being civil while you hold the upper hand.”

He goes quiet again as you both stride down the corridor, only murmuring, “ghouls like me?” under his breath questioningly. You aren’t sure he meant for you to hear it, but realizing he lacks context, you respond regardless, “You’re what would be qualified as a ‘ghoul’ above ground. A human warped from extreme exposure to radiation. I suppose it’s a bit rude sounding of a name, but I didn’t come up with it. I’ve just never seen one that glows the way you do.”

You realize that you’re moving further away from where you woke up, if you’re orienting yourself (and the vault) correctly. He speaks again as you move into a bigger connective chamber, “well, file that away with the rest of the things i need to ask more about later. and for what it’s worth, i _am_ sorry about how our first 'meeting' went down. i wouldn’t have blamed you for being more hostile, cards in hand or not.”

“It can seem like everyone up top is hostile regardless of approach sometimes. I fell in with my current group because I was usually able to take a more balanced approach. It comes in handy, if all else fails I still always have my charisma,” you quip and return his wink from earlier. Sans pulls a smile and gives you a mild, “heh.” 

“If anything, I just want to ask about the flower… thing from when I woke up, but _you_ haven’t brought _that_ up. So I have to assume that’s off limits.”

“you assume correctly.”

“Well, file that away with the things _I'll_ need to ask about later,” you respond, frustrated at how fast the topic had brought down the verbal shutters. It had been a shot in the dark chance to fish for information, but you can’t help but feel a little disappointed at killing the more-or-less polite conversation. 

He just gestures for you to move past him into a room first and you both take a moment to regard the other again, wondering at the limits of this unspoken agreement. You slide past him and into the room beyond.

**Notes for the Chapter:**

> I am so very sorry to those who have waited for this. I hope you enjoy. I have most of the next chapter written or I would not have posted this. Your kind words through this gap are the reason I soldiered on to continue writing and didn't just remove it altogether. Next chapter we'll be meeting a more robust cast of characters. Not everyone in Vault 66 is a ghoul...


	7. Chapter 7

As it turns out, the visitor check-in process is a formality, built-in from Vault-Tec’s pre-War hospitality mindset. You and Sans enter what you assume is supposed to be a welcome center or lobby and go to a kiosk at the end. When he finishes punching in information, it gives a celebratory chime and spits out a label with your name on it. The top is decorated with confetti and a tagline that says ‘You are S.P.E.C.I.A.L!’

At the disgruntled wrinkle of your nose, Sans smirks again. If he has any further commentary, he elects to keep it to himself. He then takes you a little further down the corridor into a room with structures that you vaguely recognize as an early model of decontamination arch.

He walks over to a locker on the side of the room and opens it up, pausing as you flick the lights to a brighter setting. “i keep forgetting to do that. habit, i suppose. my bad. it’ll be easier once we get to the main floors, most of the lighting there is automated by alphys. doesn’t make much of a difference to me. hence forgetting.”

He resumes his rummage through the locker and hands you a pristine vault suit with a bright reflective ‘66’ emblazoned on the back. You take it gingerly, putting together what he expects from you, “You gonna offer me free dry cleaning while I’m here too?”

“i’m going to use this opportunity to give you as long as you want to change and rid yourself of radiation, while i update the head of security on your status.”

You nod, but you feel your wariness show itself on your face despite your best efforts to rally your expression. Even knowing about Frisk, you were slowly getting edged further out of your comfort zone and into the unknown. Reading your face he chimes in quietly, “one of the things i plan to find out is what information she’s comfortable with me giving you.”

You set your mouth in a grim line and nod again, gesturing loosely to the terminal at the end of the room, “Is that what controls it?”

He nods, adding, “the lockers on the other end of the room are empty. you can stash your stuff in one of them, and then i’ll see what i can do about that dry cleaning.”

Sans leaves. You let the quiet seep in around you from the unfamiliar room, the only company to your thoughts the thrum of piping and the lights. You think about lingering here to collect yourself, the urge to try and eavesdrop to see what he says is strong. But the thought of the bizarre hypnotic flower flashes in your mind and you move with more haste.

Ten minutes later you feel similar to how you might've on a trip down into the Institute proper. Unnaturally clean, lacking in rads, and uncomfortable in a jumpsuit. If you were being honest though, the Vault 66 suit was actually far more accommodating than you expected. Maybe it was because they expected people to do everything in them when they were designed?

You take the opportunity to pack everything neatly into your duffel bag and sling it over your shoulder. Sure, Sans offered for you to leave it in a locker here, and while it seems convenient, you don't feel like you should surrender access to all of your earthly possessions with such ease. Add to that the fact that he had missed your thigh-holstered knife, likely out of misplaced modesty, and you were in much better shape than you could have been.

Stepping back out into the hallway beyond the welcoming center, Sans gives you a casual wave as he pushes himself off the adjacent wall. You see his eyes linger on the duffel for a moment, but to his credit he says nothing. Instead, he leads right into a rundown of what he and the head of security have established.

"so everything for the next few hours is going to follow a bit of a script, but what can you do?"

He seems a bit disappointed with the noncommittal shrug you offer, but you've decided it's worth keeping opinions to yourself until you know what you can of the plan. Pressing on he starts, "the head of security is named undyne. she answers directly to the overseer, and my brother and i answer directly to her. you've responded decently with me, despite our worries of first contact difficulties. but the fact of the matter remains that our vault has been deeply affected by our time underground."

You nod as he explains. At this point, it seemed obvious that they were guarded about whatever ghoulification had occurred. A vault of drastically altered people in any manner deviating from the norm would have good reason to be wary. Especially since they were isolated in their knowledge of how the world above worked.

"you're going to meet with my brother papyrus before we bring you through into the vault proper. he is going to vouch for the details i've already provided, in case i happen to have been compromised in some manner. then we'll have you meet with undyne and begin the case for finding the kid. after that it gets a little more open, but i have to assume that at some point overseer dreemurr will want to meet you at the very least. does that all sound agreeable to start?"

Chewing over all the little details and names you've just been given takes a minute, but it seems like they've decided to give a tentative olive branch. You decide to carry on with what you hope is a fairly neutral topic, "Seems promising enough. So where will this meeting take place, since no one seems to live on this floor?"

He sighs, "that's a good question. you’re an unknown in many ways. as much as i'm curious to see your reaction to the vault at large, there's also something to be said for how they'd react to you being here. a lot of us had given up on the idea of getting out one day."

There's a lot of implications packed into that last statement, and you both lapse into a bit of quiet to digest what's been exchanged. As you turn a corner you connect into the largest vault chamber so far and Sans uses the opportunity to change the topic. He points to the upper level on the far side of the two-story room, "if you follow the short hall through that door, it takes you to the old overseer’s office that you came in through."

It's a significant tidbit of information to offer you, letting you know, even vaguely, the way out. You try to decide how much weight or significance you should give it, and the feeling of his eyes on your face suggests that he's waiting for your reaction as well. You decide to push off forming opinions for just a little bit longer, "I don't remember much, but that's an awfully plush bed to leave abandoned. If my stay becomes extended am I allowed to call dibs?"

His chuckle is at least a little genuine, and you hope it's an agreement to push off making hasty decisions about one another. A sharp, loud ding sounds behind the two of you, surprising you. At some point, he'd hit the call button for an elevator behind you. It was set into the opposite wall of the chamber from the Vault entrance hallway and old overseers office, and on this level you can only imagine it will take you further down. You wonder at the purpose behind this seemingly abandoned level as you slide into the elevator alongside Sans. There are several questions you hope to have answered before you have to leave the vault behind.

Sans sets a destination for the elevator. Amusingly, the floor button that's lit no longer has the number on it but is instead represented by a crudely drawn snowflake. There are six floors in total, most having similar modifications to the buttons representing them. Snowflake appears to be the second one from the bottom. Below it is a letter 'R' and above it a water drop, what looks to be a small flame, and a symbol showing a house. The floor you assume to be the one you're leaving is the only one with the button unscathed, its pristine typeface 'S' in traditional vault format.

Leaning against the back metal wall of the elevator, you feel it shift to move as the door slides shut, and the churn of gears usher you downward. You try not to linger too long on the implications of being taken into the depths. Instead, you start back with the conversation, “So is your brother meeting us when we get off?”

“yeah. it’s been agreed that with the kid in the vault already, making a fuss over a human presence could endanger them more than it would grease the wheels for introducing you. you get to slip in unannounced so to speak. most residents wouldn’t have the context for you being here either way.”

“I appreciate you guys ensuring Frisk’s safety.”

And you do, it’s important to you that after everything else this kid has been through they don’t end up traumatized and abandoned in a ghoulified vault because of your interference. It would be almost no better then if they’d remained in Vault 100.

“I suppose this might be me hedging close to ‘personal question’ territory, but ghouls are typically long-lived. Will my presence here be more a culture shock or a reminder of how things used to be?”

“some of me dodging these questions is less you not being allowed to know, and more that i’m not sure how to answer you. in this case, i’m gonna go with culture shock, but i think that’s gonna extend both ways,” he replies after a moments consideration. You want to ask more, but you also realize that you’d be cut off as your descent has slowed.

After another second of stillness and the clinking of unseen mechanisms, the door slides open and some of Sans’ hesitance to commit to answers makes more sense. On some level, you’d made your conclusions about what was hidden in Vault 66 based on what you could see and explain away. The population had dwindled, and Sans’s was obviously a ghoul in the later stages of development as he’d adopted glowing ones’ features, so naturally, it was a ghoul vault.

Culture shock was right. Waiting outside the elevator for the two of you is another figure that takes you aback in just how very damaged they are. He stands a full foot and a half taller than you do, and the light being let into the elevator is tinged a light orange as he also shows patches of musculature that is luminescent. But most notable is the skeletal face of this ghoul hybrid, not so much malicious or terrifying as it is startling. Dim orange irises look you over with a fervor under the arch of wide orbitals, giving the two of you both a surprised countenance towards the other.

At some point during this inspection, you realize the elevator door hasn’t shut because Sans had the good sense to step into its path. You clear your throat and do a quick rub of your eyes to ensure you’ve taken everything in correctly, but the hulking figure is still present. He breaks out into what you think might be a leer until his words make it obvious that it’s meant to be a grin, “WELCOME TO VAULT 66! I’M PAPYRUS!”

His hand extends out to you, also sinuous and telltale of a ghoul, and without knowing what to say otherwise, you reach out and shake it with a modist timidity. The handshake he gives you is so rough and earnest that you can’t help but have something between a huff and a laugh shaken out of you.

**Notes for the Chapter:**

> Double bill weekend, likely because of my guilty conscious. But we've officially met Papyrus! He'll get more of a role in the next chapter, and then we'll get around to Undyne shortly thereafter. The two I'm most looking forward to are Alphys and Frisk interacting with the MC though. Please let me know what you think, as usual. Your comments and kudos feed me.


	8. Chapter 8

They seem to have set up some sort of temporary quarters in the residence closest to the elevator. Immediately following your introduction to Papyrus and subsequent mild shock, you were escorted into the rooms off to the side and not given a further tour of the area as you had expected. 

You’ve opted to try and take everything in stride, given that trying to guess at circumstances keeps coming up short. There doesn’t seem to be any immediate danger, and they clearly aren’t sure how much of themselves they want to give away. You’re just trying to turn off the niggling, paranoid part of your brain that keeps trying to convince you that they’re full of hidden malice. The last half hour has been a descent into reasoning with yourself on auto-pilot, while Sans and Papyrus seem to be at odds about how to handle you falling into their lap. 

For the most part, it’s wound up with you being ignored, while they try to talk their way through every possibility. You aren’t sure if it’s the isolated nature of the vault, the lack of personal familiarity, or the circumventing way in which they’ve discussed everything, but you don’t think you’ve learned anything of value by listening to them. 

Papyrus comes into the small galley-style kitchen that you’ve wandered into and throws a small glance your way before he swings into prepping something. Something like frustration seems to have followed him. Working with a single-minded focus on the food, you take the opportunity to watch him and desensitize yourself to his appearance the best you can. He’s far more of an adjustment to visually accept than Sans, though in his case it was mostly because of size than anything. He was hulking, more akin to the height and breadth of a Super Mutant than any ghoul you had encountered in the past. Your eyes trace his busy handiwork and watch his ligaments extend and flex in his wrists and arms as he works. 

Aside from a brief glance at you as you tense when he pulls out a kitchen knife, he continues his task under your watch without reaction. After a minute more of prep, he slides everything into a bowl together and then stands back to his full height to pass the bowl over to you. You take it, more surprised than anything. Then you look down with the realization that you paid no actual attention to what,  _ precisely _ , he had prepared. 

The bowl was cold to the touch, and the food inside glistened somewhat malevolently. However, years on the surface had hardened you to this kind of experience and you weren’t a picky eater. Relatively certain he hadn’t poisoned it while aware you were watching, you take the fork he offers and dig in. 

Whatever dark cloud of emotion seemed to have followed Papyrus into the kitchen with you, it vanishes as you lean against the counter and gulp up the food greedily. His expression stretches back into a grin, and you try to push down the quaver of fear it pushes up your spine. Instead, you polish off the bowl, noting that it was both unlike anything you’d ever eaten and also not as bad you might have imagined. A little sweet for what you might have otherwise called a pasta dish. 

The fork clatters into the bowl before he speaks up, his voice gentler than before but still unexpectedly loud, “I’M GLAD YOU LIKED IT. I’M USED TO PICKY EATERS.”

You give a small smile, “There aren’t always enough resources up top to be picky with. It doesn’t hurt that I’m not positive how long its been since I’ve eaten.”

“HMM. SANS, YOU DIDN’T FEED HER?”

“we didn’t have much of an opportunity to eat bro, we were busy,” Sans echoes in from the other room of the small vault quarters. 

“WELL, I HOPE YOU ENJOYED IT HUMAN,” Papyrus responds. You aren’t used to this titling, but you smile at him and give a small nod all the same. He doesn’t seem to mean anything by it, and whatever else the vault is full of it’s obviously no longer humans. Papyrus smiles back and you manage not to flinch, then he turns and gestures for you to follow him back out of the kitchen. 

Stepping back around the corner, you find Sans at a terminal in the far corner, flicking through what looked to be footage of various corridors. He turns back and you are once again mildly struck by the alien glow of his eyes. This time he too gives you a bit of a smile, and you realize that you must have been visually broadcasting how on edge Papyrus’ appearance made you if they are trying all of these little gestures with you. You sit on the threadbare couch and take a moment to settle your nerves, but the two of them don’t immediately jump back into a back and forth of options. Instead, they seem to be taking you into consideration. 

“So what exactly is the plan from here?” you ask, seeing that you might need to let them know that you’re on board. They share a glance, but Papyrus moves to take a seat.

“WE WANT TO HELP YOU FIND THIS FRISK, FIRST AND FOREMOST. BUT YOU NEED TO BE PREPARED FOR WHAT YOU’RE GOING TO WALK INTO AS WE GO FURTHER INTO 66. YOUR REACTION TO MEETING ME HAS CONFIRMED SOME OF WHAT WE ALREADY GUESSED, OUR APPEARANCES DOWN HERE ARE… NOT NORMAL.”

He addresses all of this in a matter of fact way, but you can tell that it was a disappointing thing to have confirmed. It twinges a bit to realize that you’ve confirmed something so disheartening, and you make a mental note to try to talk with him about it later. Sans, likely aware of his brother’s discomfort, takes over.

“the thing is, as odd as we must look to you, no one in our vault looks human anymore. you will also be an outlier while we stay down here and we have to account for the potential interest of the residents. so we need you to agree to be accompanied by myself, papyrus, or undyne until we get an idea of how the rest of this will work.”

“Is this more of a glorified house arrest? Because I would rather know upfront if it is. You guys don’t seem to know what to make of me, and I can appreciate that, but I’m similarly lost and without any sort of council to keep,” you respond. Though it starts off a little overly gruff, you manage to smooth the delivery by the end of the comment. Or at least you hope. 

“honestly? i’m not positive. a lot of this is subject to overseer approval, and undyne is the only one who holds a lot of sway with overseer dreemurr. he’s not responded to my initial inquiry yet, and so i’ve had to hedge my bets with the information you’ve gotten. even though i’m sure you think it hasn’t been enough, know that if they decide that i compromised vault security bringing you down here, my goose is cooked.”

“SANS, YOU KNOW I WON’T LET THAT HAPPEN.”

“it’s not just my goose that would be cooked either, despite paps’ protests. you need to make a good impression on undyne, because you’re accountable for whatever she thinks of both you and the small fry,” he finishes with a pointed look at you. 

“Well. No pressure or anything, right?” you respond with a halfhearted chuckle. When they both exchange a glance, you clear your throat and move on, “Alright, so impressions are important. When do we leave to meet her?” 

“WELL, THAT’S THE THING. SHE’S WAS SUPPOSED TO MEET ME HERE, BUT SHE HAD TO RESPOND TO A SUB-LEVEL ALERT.”

You share a wary look with Sans, “Does it have anything to do with Frisk or…” 

“it correlates to the location of the video i shared with you before, i think there’s a chance that it could have been. if it was, then it means that the hold-up is likely due to a lack of cooperation. undyne is likely similarly startling in her appearance, there is a chance that they believe her to be some form of monster.”

You decide to hold your tongue on that. Instead, you move to the logical conclusion, “So the two of you want me to sit tight in here while you go figure out what happened?”

“actually, i was wondering if you would be willing to come with me. we might need to rely on your appearance to get frisk on board. are you willing to accept being mildly used as a pawn in exchange for escaping house arrest?”

“I WOULD BE MONITORING REMOTELY FROM SECURITY. SINCE YOU DON’T HAVE YOUR OWN PIP-BOY, I’LL HAVE TO SEE IF WE HAVE ANY EMERGENCY COMMS.”

“I suppose I’m willing to accept being used, so long as you understand that I’ll eventually levy it in my own favor. I scratch your back if you scratch mine, right? Especially if my terms of stay down here is going to be merit-based.” 

Sans and Papyrus share another look, this one seeming to convey a little more significance. Papyrus breaks it to look you over again, “I BELIEVE THAT WOULD BE CONSIDERED FAIR.”

You wait for a moment for them to elaborate, but everything in you gets the impression that you’re being run through some kind of trial. When neither of them continues, you give a sigh, “I’m a creature of action. I would have been more upset if you’d wanted me to sit here and twiddle my thumbs. Fair is more than I would usually hope for, and it’s all I can ask for Frisk.” 

You stand and the action seems to spur the two of them into action. Sans turns back to the console in front of him, flicking through the video feeds again while Papyrus stands and observes you uncertainly. 

“VERY WELL, LET ME SEE WHAT I CAN DO. I’LL BE BACK SHORTLY.”

He turns and leaves, and you are left mildly listless once more. Finally, after a fifth click of the keyboard in the silence, you bluster out with, “Have I come across as rude?”

Sans stops, but he doesn’t turn back to face you immediately. Rather than wait for him to reply, all of the nerves that you’ve shoved back and compartmentalized threaten to burst forth in a frisson of uneasiness. You restrain most of it, but still, you can’t help but let some of it trickle over now that there are metaphorical cracks in the dam. 

“I’m sure, given the close quarters you guys must keep, I might seem a bit brash. Most of that can be chalked up to circumstances that are basically out of my control. This isn’t the first time I’ve been a captive. Hell, it’s not even the first time I’ve had to worry about offending my captors. It is, however, the first time I’ve had to worry about it without being able to  _ tell _ .”

He gives a raspy sigh, turning to you, “no. you haven’t been rude. all things considered, you’ve been pretty damn tolerant. you just have no idea what you’ve stumbled into.”

“Then, please,  _ tell me _ .”

His eyes lock with yours, and perhaps he sees mirrored there the hopelessness that you’ve felt since stumbling down into this damn mess. He obviously sees something, because he gives you a small nod, “alright. once we get downstairs, i’ll tell you everything i think i can get away with. deal?”

“I’m guessing you need to wait for us to be on the move because Papyrus wouldn’t approve?”

“not exactly. but my goose is already cooked, i’d rather not get started on his. ultimately he wants to wait for undyne to be the voice of approval. which wouldn’t be a problem if undyne were here.”

“You think that something happened to her?”

“heh, if you knew undyne you wouldn’t be saying that. it’s why papyrus won’t even so much as consider the possibility. things don’t really happen to undyne, she happens to them. but... yeah. i think something might have happened to her.”

**Notes for the Chapter:**

> How do we feel about chapter titles guys? I'm mildly tempted to go back and start naming them. Also! Next chapter we start getting into mild action. I'm also hoping that I can gently push the word count per chapter up from here. Right now they've been comfortably hovering around the 2k marker. We'll see. I just like to go until I stumble across a natural break. 
> 
> As always your thoughts and opinions are greatly appreciated!


	9. Chapter 9

The elevator of the vault may quickly become the place in the vault you’re most comfortable with. Perhaps they’ll let you set up a cot. It’s a noisy and slow thing though, and given the quiet Sans seems content to leave while deep in thought, you are left with little to do except listen to the symphony of its mechanical sputtering. You’re curious about what the ‘R’ floor marker means for the venture you’re taking, but you also aren’t sure if prying before Sans has even had a chance to start explaining is a good idea. 

As the lift slows its crawling descent, Sans gives a low hum that sounds a bit like approval before it’s drowned out. He turns to you and gives you a long look that draws you into the present moment, the glow of his eyes bearing heavily into your own. Stepping over to stand in front of you, he reaches to your arm and flicks off the comm Papyrus strapped to your arm with a quick movement. 

Hovering close, he speaks to you in an even more hushed voice than his previous low rumble, “so here’s what i’ve got. our vault failed early on in the apocalypse. all of us who have survived did so through a willingness to accept mutations, and undyne is no exception.”

Sans takes a second to back off from you, his eye contact faltering to the corner above you as he talks. As you take in the tension in his stance, you notice his hand clenching and unclenching slowly as he speaks.

“the first overseer though, the scientist who ensured that we survived, he didn’t catalog all of our changes. life or death situation, protocol no longer mattered, y’know? i think the thing that harassed you earlier is one of his ‘off the record’ experiments.”

His eyes flick back you, the sense of urgency you recognized behind them was bleeding into his words, “i know you and the kid don’t exactly realize what you’ve stumbled into. i can’t promise your safety, and as much as i resent being part of vault security, i hate that i can’t offer you that.”

Sans kept eye contact a beat longer, then looked over to your arm and flicked the comms back on. Papyrus’s voice crashed through the tinny speaker, “-METHING HAPPEN? I DON’T SEE MOVEMENT ON ANY OF THE RUIN SENSORS...”

You see Sans flinch away, though you can’t tell if it’s the volume or the concern in Paps’ that’s the cause behind it. Trying to find a way to answer his confession from a moment ago, and also the concern that’s being broadcast by Papyrus, you pick up the communicator and hit the button with a wink to Sans. He’d been lifting his Pip-Boy to answer but watches you move into action instead.

“Sorry Papyrus, it seems like I knocked the comm offline. I stumbled as the lift came to a halt. We just got it working again.”

“SANS, PLEASE KEEP A BETTER EYE ON THE HUMAN!”

Sans’ eyes widen briefly and flicker back to you with the ghost of appreciation in his expression. He clears his throat and replies, “yeah, paps, that’s my bad.”

“WELL, AS I SAID, NO MOVEMENT. LET ME KNOW IF ANYTHING CONTRADICTS THAT.”

“copy.”

There is a comfortable silence that falls as you give a light smirk, which he returns before stepping out of the elevator. Aware you’re being monitored now, you keep your questions to yourself for the moment. Your tapering confidence mildly bolstered by what you’ve seen of Sans so far. 

The long, narrow corridor you move into is more what you expect of a Vault-Tec ruin nowadays, rust lines running the walls frequently, the paneling ill-fitting and scuffed around the edges. Everything appeared to still be run, however, and the dim emergency light overhead emitted an annoying thrum. 

Finally, the two of you reach a double door off to the left and he runs a cable from his Pip-Boy to open it. The sound of a lock shifting in the metal gives you a start, which causes Sans to chuckle and lift a finger to his lips. You cast a dirty look at him, but before you can say anything, Papyrus crackles through your speaker.

“16 THROUGH 14R, CLEAR.”

Sans flicks a knob on his Pip-Boy and replies, “copy.”

At your inquiring gaze he gestures up at the camera further down the way back towards the elevator. “sectors of camera coverage,” he answers in a low rumble. 

You make a soft sound of appreciation and Sans turns to push onward, the noise of the doors fractional after their method of unlocking. The room beyond is larger than you’re prepared for, a courtyard with a massive dead tree in the center of it. Its blackened branches more reminiscent of life up top than you’d expect out of a plant in a vault. 

The room isn’t as large as the atrium you and Sans crossed through earlier, but it is sizable. You spot three doors besides the one you came through. Two have been left gaping and open despite the vault’s secure-door system, further signs of the disrepair that seems to plague this level. 

As you step into the courtyard with the tree behind Sans, you can help but walk up to it. It’s much larger than you’re accustomed to any plants being, dead or otherwise, and the bark is a peculiar off-grey. As you look down at the base, you find that a few odd and weedy growths are nestled with it, still alive. It would normally give you a bit of hope, seeing life push through here the way it always had aboveground. But the weeds are a familiar shade of discomforting green and wrapped around the roots of the tree in a way that seemed almost choking. 

Sans’ voice breaks you from your consideration, “looks like we’re going to have to press further in. no one’s home.”

You tear your eyes away from the tree and see that Sans has moved over to the other operational door in the room, fiddling with a fairly sophisticated panel that was located to the side of it. Unlike the rest of the area around it, you realize the door looks to be in good condition. 

As he looks up from his Pip-Boy readout, Sans notices you looking between him and the door and shrugs, “or at least, they aren’t answering if they are.”

“I didn’t expect anyone to be down here,” you counter. It’s the truth. If this level was borderline functional, why bother to keep it running at all?

“it wasn’t likely we would get an answer. hence the lack of warning. they have feed access too,” Sans mentions, gesturing to the camera mounted in the far corner of the room. This doesn’t answer any more questions for you, other than offering further verification that this floor is actually inhabited, but you decide now is not the time to press. 

“You said Undyne was responding to Frisk down here. Is it likely that the… neighbors interfered?” you ask. Sans seems confused for a moment and then follows your look back to the door. His chuckle surprises you. 

“interference from the neighbors on frisk’s behalf from ‘the neighbors’ would not be a bad thing. but it’s highly unlikely,” he replies, a melancholy note on the end of the statement. He shakes it off and nods towards the door standing open along the opposite wall, “i’ll take point.”

Sans seemed uncomfortable with taking the lead, but also trying not to let that bleed through. He seemed to feel some kind of responsibility for the situation, but also didn’t want to discuss it on terms outside of his own. You nodded and motioned for him to take the lead. 

“emergency lighting should keep things mostly lit, but stay close enough the pip-boy can make up for what doesn’t work,” he continues, walking through the door. As you move through after him, you come to the end of another long corridor branching out to your right. On your left is another door that appears nonfunctional, this time wedged partially open with debris. Only darkness greets your curious glance in. 

“there’s not much through there, but i can stick my arm in if you want,” Sans says, gesturing broadly to his arm. You shake your head, the blockage in the doorframe didn’t look recently disturbed and if it wasn’t on Sans’ radar, then you weren’t going to needlessly slow things down. The lingering pause in the conversation causes you to realize his attention was caught elsewhere, lingering in the doorframe behind you. 

Turning your head, you squint to see whatever has caught his eye in the dark room beyond. Your angle wasn’t what it could be though, and although you can’t illustrate this, you see Sans move out of the corner of your eye regardless. Cautiously flicking one of the knobs on his Pip-Boy, the incandescent screen knocks up into an eerie blue-green glow. Mildly wraithlike in the glow, he moved forward with his arm outstretched to light the blocked off room.

You look back down the hall before turning once more to the jammed door, scattered with sharp shadows from the added brightness of the Pip-Boy. Curling through the debris blocking the door was a thick, fibrous vine that contracted away from light. The color of it washed out into a dusky grey, but on some level, it registered as the same plant you had encountered previously. 

Sans turned, his facial expression grim, and you caught him clenching and unclenching his fists again as he moved away from the blocked door with haste. Though the added light moved away with him, the shadows of the door lingered in your vision as a hazy imprint. As it faded back to shadow in the dim emergency light, you think that you can see the same motion that caught his eye, a casual curl of pointed shadow against the metal doorframe. You immediately turn away, picking up the pace to close the growing gap with him.

“Sans-” you begin after a silent jog to his back, both of you moving quickly enough that caution is no longer being regarded. It was an irrational response to fear, you recognized the desire for aversion. But before you could say anything to either chastise him or recognize the obvious and creeping threat you’d both encountered, he signaled for you to stop. 

Or at least you assumed that was what it was he signaled for, it was fairly negatory for a hand motion. He led you through a small door after a few more yards, dipping into a small, defunct storage room of sorts. 

“we need to mark 11R as dark for the moment,” Sans began after a breath, and you realize it is only indirectly to you and meant for Papyrus. 

“IS THE HUMAN OKAY?” 

You weren’t sure if the gesture was touching or foreboding, but you manage a slightly tense, “Mhmm.”

“...STAY SAFE, SANS.”

The white noise of the line cut out as he did and Sans leaned his head back against the wall. Rubbing his hands against his face, Sans pushed up to look back at you a moment later, pulling a grin.  
“the worst part is that this door just makes me feel a little better. you’ve seen what it can do,” he paused and collected himself, “but we know it’s here now. possibly because it wants us to. that’s something.”

You nod, uncertain of what else you can offer in your own unease, and decide to take quick stock of the room and give him a moment to gather himself. As you move to shift a table for better access, a pitched whine comes from the receiver attached to you. Before you can examine further, it turns to a sort of buzzing noise and then shifts into an unfamiliar panicked voice speaking, ‘-zzz, i hate to interrupt your panic vibe, but undyne says i should stop waiting…”

“napstablook?”

“............yeah,” came a staticky and uncertain reply.

“where are you? where is undyne?” Sans replied, stepping over to you with sudden fervor and gingerly snagging the receiver. 

The voice that answers suddenly sounds even meeker at Sans’ response, “the base level of the vault… she says you should come here…” 

There is a muffled conversation on the other end of the connection, a hard and flat voice answering the quavering Napstablook that you had to assume was Undyne. You wonder briefly at how they had tuned into your comm channel, or why they had chosen that moment to make themselves known. The meek voice returns, “yeah. PLEASE come down here. she says i can go home after you get here.”


End file.
